1. Field of the Invention
The present invention relates to a light interceptor which partially intercepts light in a viewfinder of a camera to vary the size of a field frame of the viewfinder.
2. Description of the Related Art
In general, a camera includes a viewfinder through which a photographer can view an object to be taken (or photographed) by a photographing lens system. The viewfinder is comprised of, for example, a finder lens system and a hollow finder block having a generally rectangular cross-sectional shape for holding the finder lens system. The finder block is provided in the camera body, so that the rear end of the finder block is attached to an ocular window which opens into the back surface of the camera body.
In a camera such as a lens shutter type camera, in which the photographing lens system is separate from the finder lens system, a finder window opens into the front surface of the camera body. The finder block is attached at the front end thereof to the finder window. Consequently, an optical image of an object to be photographed is conveyed from the front end of the finder block to the finder lens system through the finder window.
In a camera such as a single lens reflex camera, in which the photographing lens system constitutes a part of the finder lens system, the optical image of the object taken by the photographing lens is conveyed to the front end of the finder block and then to the finder lens system, through a movable (rotatable or tiltable) mirror or a prism, etc.
Recently, cameras having different photographing modes, including a panoramic mode, which can be selected by a mode selection switch to take a panoramic picture have been proposed.
In such cameras, upon taking a panoramic picture, an optical image of an object to be taken is exposed on a partially elongated area of a picture plane of a film which is obtained by partially removing (i.e., not exposing) the upper and lower edges of the picture plane for one frame of the film.
Accordingly, a viewfinder in a camera which can take a panoramic size picture is provided with a light intercepting mechanism which intercepts light to the upper and lower edges of the field frame corresponding to the area of the film which is not exposed.
In a conventional partial light interceptor, a pair of upper and lower arms are provided. The arms are supported at the side portions of the finder block close to the front end thereof to-swing in the upward and downward directions. A mask member, which is attached to the front end of each of the upper and lower arms, extends to lie in front of the finder block.
The upper and lower arms are swingable in opposite directions in association with a mode selection switch, which is actuated to change the photographing mode between the standard size picture mode and the panoramic size picture mode.
When the panoramic mode is selected by the mode selection switch, the upper and lower arms swing downward and upward, respectively, so that the mask members of the upper and lower arms move in front of the finder block to partially interrupt the field frame of the viewfinder. The limited field frame corresponds to the exposed film area of the panoramic mode.
When the standard mode is selected by the mode selection switch, the upper and lower arms moved (swing) upward and downward, respectively, so that the mask members move upward and downward, respectively. Consequently, the mask members are retracted from the field frame of the viewfinder.
However, in the conventional partial light interceptor, since the mask members swing (rotate) along circular loci about the supporting shafts of the arms in front of the finder block through the respective arms, it is necessary to provide, above and below the finder block, a space large enough to prevent the mask members from interfering with the elements located around the finder block, thereby increasing the size of the camera body.